1. Field of the Invention
The present invention relates to movable body apparatuses, exposure apparatuses and pattern formation apparatuses, and device manufacturing methods, and more particularly to a movable body apparatus equipped with a movable body that moves in at least one axial direction along a predetermined plane, an exposure apparatus and a pattern formation apparatus equipped with the movable body apparatus, and a device manufacturing method that uses the exposure apparatus or the pattern formation apparatus.
2. Description of the Background Art
Conventionally, when manufacturing electron devices (microdevices) such as semiconductor devices (integrated circuits and the like) and liquid crystal display devices, an exposure apparatus such as a reduction projection exposure apparatus by a step-and-repeat method (a so-called stepper) or a reduction projection exposure apparatus by a step-and-scan method (a so-called scanning stepper (which is also called a scanner)) is relatively frequently used in a lithography process.
In this type of exposure apparatuses, in order to transfer a pattern of a reticle (or a mask) to a plurality of shot areas on a substrate such as a wafer or a glass plate (hereinafter, generally referred to as a “wafer”), a wafer stage that holds the wafer is driven in two-dimensional directions by, for example, a linear motor or the like. In particular, in the case of the scanning stepper, not only the wafer stage but also a reticle stage is driven with a predetermined stroke in a scanning direction by a linear motor or the like.
Conventionally, a laser interferometer was used for position measurement of the stage in general, and besides the laser interferometer, an encoder was also used. When the encoder is used for position measurement of the stage, the apparatus-specific measurement errors tend to occur due to scale-specific manufacturing errors, and errors caused by attachment of a scale (including deformation occurred when attaching the scale, and the like). Meanwhile, the laser interferometer can generally obtain an absolute length that does not depend on the apparatus because it uses a physical quantity, which is a wavelength of light, but at the same time, since the laser interferometer has measurement errors due to air fluctuations generated by influence of temperature variation and/or temperature gradient in an atmosphere in a beam path of the laser interferometer, the stage positioning precision is degraded. Therefore, in conventional methods, a stage device that complementarily uses the encoder and the laser interferometer has been proposed (e.g. refer to Kokai (Japanese Unexamined Patent Application Publication) No. 2004-101362).
As a method of using the encoder and the laser interferometer in a complementary manner, which is the most realistic (practical) method, a method can be cited in which by driving a stage at an extremely low speed and spending sufficient time to perform measurement, measurement values of the interferometer are made to be reliable, and a calibration table of encoder measurement values is created using the measurement values of the interferometer, and when performing actual exposure, the exposure is performed using only the encoder measurement values and the calibration table.
However, with the encoder described in Kokai (Japanese Unexamined Patent Application Publication) No. 2004-101362, and the like, a linear scale needed to be installed at a position that was far away from a wafer mounting position on a wafer stage (from a position to which an exposure light is actually irradiated), and therefore the measurement points of the encoder and the interferometer were away from each other, and hence it was difficult to obtain accurate measurement values due to being affected by the Abbe error caused by a rotational motion of the wafer stage, local deformation of the stage, and the like.